Electric lamp filament support



0, 1966 F. A. MosBY 3,270,238

ELECTRIC LAMP FILAME'NT SUPPORT Filed Feb. 7. 1963 ITWQTTL-OT: FTEd A.MOSbH b mf His A lr crowe3 United States Patent 3,270,238 ELECTRIC LAMP FILAMENT SUPPORT Fred A. Mushy, Cleveland, Ohio, assignor to General Electric Company, a corporation of New York Filed Feb. 7, 1963, Ser. No. 257,027 Claims. (Cl. 313-279) This application is a continuation-in-part of my application Serial No. 220,444, filed August 30, 1962, and now abandoned. This invention relates generally to electric incandescent lamps and more particularly to auxiliary filament supporting structures therefor.

It is an object of the invention to provide a novel form of filament support structure which is particularly adaptable for use in lamps having a pinch seal formed at at least one end of the lamp envelope and through which is sealed at least one lead-in conductor to which the filament is connected.

Due to the absence of internal glass parts such as arbors and stems, there is no structure on which to anchor or support the filament support member itself, other than the envelope. Accordingly, in lamps of the tubular double ended type having a longitudinally extending filament connected at its ends to lead-in conductors which extend through respective pinch seals at opposite ends of the envelope, it has been the practice to support the filament, at spaced points along its length, by support members in the form of disks or wire structures which engage with the filament and with the envelope wall whereby to support the filament in the axis of the envelope from the envelope wall. While such structures fulfill their function, there are certain disadvantages such as time consuming, and therefore expensive, assembly methods required for the wire supports, or limitations on types of materials which may be used for the disk supports.

Briefiy stated, and in accordance with one aspect of the invention, in the case of the double ended lamp types there is provided at either one end or at both ends of the envelope, a support in the form of a U-shaped, or hairpin shaped, wire having the ends of its legs embedded in a pinch seal at the end of the envelope and having a loop in its bend encircling the filaments at a point intermediate its length. Similarly, in the case of a single ended lamp having a pinch seal at only one end of the envelope, with both lead-in conductors extending through said pinch seal and connected to respective ends of the filament, there is provided a generally U-shaped wire support having its legs embedded in the pinch seal in spaced relation to the lead-in conductors and having at its bend or bight portion a loop or hook supporting the filament at a location intermediate its ends.

Further features and advantages of the invention will appear from the following detailed description of species thereof and from the drawing wherein:

FIG. 1 is a side view of a double ended lamp provided with a support member in accordance with the invention;

FIG. 2 is a vertical elevation, in section, illustrating a preferred method of assembly of the lamp envelope and filament;

FIG. 3 is a side view of a lamp embodying two support members in accordance with the invention;

FIG. 4 is an elevation of a single ended lamp provided with a support member in accordance with the invention; and

FIG. 5 is a cross section through the pinch seal along the line 55 in FIG. 4.

Referring to FIG. 1 of the drawing, the lamp comprises an elongated tubular envelope 1 of vitreous material such as glass or quartz having a flattened pinch seal 2 at each end thereof which may be pressed to an I-shaped cross section. A filament 3, preferably a coil or coiled-coil of tungsten wire, extends axially of the envelope 1 and is 3,273,238 Patented August 30, 1966 connected at its ends to lead-in conductors 4 which extend through and are hermetically sealed in the pinch seals 2. When the envelope 1 is of quartz, the leads 4 preferably consist of molybdenum wires having extremely thin, foliated portions 5. Straightened end or leg portions of the filament are preferably attached to the respective foliated portions 5 within the pinch seal 2, preferably by welding and with a tab of platinum interposed therebetween. The envelope preferably contains an inert gas filling and may also contain a reactive atmosphere such as a halogen, particularly iodine as disclosed and claimed in Patent 2,883,571-Fridrich et al.

In accordance with the invention, the filament 3 is supported at a point intermediate its length by a U-shaped wire member 6, preferably of tungsten, having the ends of its legs embedded in one of the pinch seal 2 at opposite sides of the lead wire 4, and having a loop 7 at the center of its bend encircling the filament 3 at its midpoint. It will be evident that the support member 6 is firmly anchored in the pinch seal 2. The legs of the support member preferably extend closely adjacent opposite sides of the inner wall of the envelope 1 and are additionally supported thereby in cases of severe vibration.

In a preferred method of assembly of the lamp, as illustrated in FIG. 2, the legs of the support member 6 are spread apart sufficiently to frictionally engage opposite sides of the inner surface of the wall of the envelope 1. In order to further assure proper centering of the support 6 in the envelope 1, the outer end portions 8 of the legs of the support are bent slightly with respect to the remainder of the legs so as to engage the envelope wall for a substantial length, say about five to ten millimeters, thereby avoiding tilting of the support in the envelope such as might occur if only the very tips of the legs were to engage the envelope wall. Then, with the envelope in a vertical position, the assembly of filament 3 and lead wires 4 is threaded into the envelope from the top thereof and through the loop 7 in support 6. The filament assembly is supported by any suitable means engaging the upper lead wire 4 and resting on the upper end of envelope 1. Then, in known manner, the filament 3 is stretched slightly by pulling down on the lower lead wire 4, and the lower end of the envelope 1 is softened by heating and then compressed by a pair of jaws to form a pinch seal. The other end of the envelope 1 is then heated and pinch sealed, after which the envelope is evacuated and filled with the desired atmosphere through an exhaust tube which is subsequently tipped off close to the envelope as shown at 9.

In an alternative method of assembly, the support 6 may first be attached to the filament 3 by clamping or closing the loop 7 upon the filament 3, after which the assembly of filament 3, lead wires 4 and support 6 is threaded into the envelope.

In FIG. 3 there is illustrated a lamp which is somewhat longer than that shown in FIG. 1 and wherein a support member 6 is provided at each end of the envelope 1 so that the longer filament 3 is supported at spaced points by the loops 7 of the respective support 6.

The single ended form of lamp shown in FIG. 4 comprises an envelope 10 which may be formed from quartz tubing and which has a pinch seal 11 at one end in which are hermetically sealed the foliated portions 12 of a pair of molybdenum lead-in wires 13. A helically coiled tungsten wire filament 14 is arranged in V-shape with its ends connected to the foil portions 12 of respective lead wires 13, the said end portions of the filament coil each preferably containing an insert or mandrel wire 15. In accordance with the invention, the filament 14 is supported at its apex by a hook or loop 16 in the bend or bight portion of a generally U-shaped tungsten support 3 wire 17 having the ends of its legs embedded in the pinch seal 11.

The envelope 10 may be filled with a gas such as argon and a small quantity of iodine which functions as a regenerative getter to return'to the filament 14 tungsten vaporized therefrom, whereby to maintain the envelope clean and free from blackening. The evacuation and gas filling is performed through the end of the length of tubing of Which the envelope 1 is constituted, the said tubing being necked in and subsequently tipped off at 18. During formation of the pinch seal 11, with the lead wires 13 supported in a sealing head and carrying the filament 14, the support member 17 may be supported Within the said quartz tubing by a hook on the end of a length of wire exending upwardly through the quartz tubing and which is removed after the pinch 11 has been formed.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric incandescent lamp comprising an envelope of vitreous material having a pinch seal at one end, a lead-in conductor extending through said pinch seal, a filament in said envelope connected to said conductor, and a support member for said filament separate and distinct from said lead-in conductor and comprising a generally U-shaped Wire having end portions of its legs embedded in and terminating within said pinch seal in spaced relation to and electrically insulated from said conductor, the bend of said U-shaped Wire having therein a loop supporting the filament at a location spaced from its connection to said conductor.

2. An electric incandescent lamp comprising an elongated envelope of vitreous material having pinch seals at its ends, a lead-in conductor extending through each said pinch seal, a filament extending longitudinally of said envelope and connected at its ends to respective said lead-in conductors, and a support member for said filament comprising a generally U-shaped wire having end portions of its legs embedded in one of said pinch seals at opposite sides of the associated lead-in conductor, said legs extending longitudinally of and at opposite sides of said filament, the bend of said U-shaped wire having therein a loop encircling the said filament at a location intermediate its length.

3. A lamp as set forth in claim 2 wherein a said support member is provided at each end of said envelope with the end portions of the legs of said member embedded in respective said pinch seals and the loops in the bends of said members encircling the filament at spaced locations intermediate its ends.

4. An electric incandescent lamp comprising an elongated tubular envelope of vitreous material having pinch seals at its ends, a lead-in conductor extending through each said pinch seal, a filament extending longitudinally of said envelope and connected at its ends to respective said lead-in conductors, and a support member for said filament comprising a generally U-shaped Wire having end portions of its legs embedded in one of said pinch seals at opposite sides of the associated lead-in conductor, said legs extending longitudinally adjacent opposite sides of the inner wall of said envelope, the bend of said U-shaped Wire having therein a loop encircling the said filament at a location intermediate its length.

5. An electric incandescent lamp comprising an envelope of vitreous material having a pinch seal at one end, a pair of lead-in conductors extending through said pinch seal in side-by-side relation, a filament in said envelope connected at its ends to respective said conductors, and a support member for said filament separate and distinct from said lead-in conductors and comprising a generally U-shaped wire having end portions of its legs embedded in and terminating within said pinch seal in spaced relation to and electrically insulated from said conductors, the bend of said U-shaped wire having therein a loop supporting the filament at a location intermediate its ends.

References Cited by the Examiner UNITED STATES PATENTS 1,600,563 9/1926 Proctor 313279 JOHN W. HUCKERT, Primary Examiner.

R. F. POLISSACK, Assistant Examiner. 

1. AN ELECTRIC INCANDESCENT LAMP COMPRISING AN ENVELOPE OF VITREOUS MATERIAL HAVING A PINCH SEAL AT ONE END, A LEAD-IN CONDUCTOR EXTENDING THROUGH SAID PINCH SEAL, A FILAMENT IN SAID ENVELOPE CONNECTED TO SAID CONDUCTOR, AND A SUPPORT MEMBER FOR SAID FILAMENT SEPARATE AND DISTINCT FROM SAID LEAD-IN CONDUCTOR AND COMPRISING A GENERALLY U-SHAPED WIRE HAVING END PORTIONS OF ITS LEGS EMBEDDED IN AND TERMINATING WITHIN SAID PINCH SEAL IN SPACED RELATION TO AND ELECTRICALLY INSULATED FROM SAID CONDUCTOR, THE BEND OF SAID U-SHAPED WIRE HAVING THEREIN A LOOP SUPPORTING THE FILAMENT AT A LOCATION SPACED FROM ITS CONNECTION TO SAID CONDUCTOR. 